Certain classes of internally pressurized aircraft fuselages, such as are found in passenger planes, can beneficially employ near-elliptical cross-sections. For example, U.S. Pat. No. 6,834,833 to M. K. V. Sankrithi discloses the use of an aircraft having a fuselage 10 with a quasi-elliptical, or near-elliptical cross-section that is wider than it is tall. Representative front-end and a top plan cross-sectional views of this class of fuselage shape are illustrated in FIGS. 1A and 1B, respectively, wherein the fuselage comprises a rigid, light weight shell 12 having respective opposite, closed nose and tail ends 14 and 16. This cross-section efficiently encloses a main deck cabin 18, typically provisioned as a spacious and comfortable twin-aisle, seven-abreast cabin, together with a cargo container 14 (typically a LD-3-46W or similar, standardized type of container) in a pressurized lower deck hold 20. This twin-aisle fuselage cross-sectional shape has also been shown to provide a perimeter-per-seat ratio comparable to that of a corresponding single-aisle, six-abreast, conventional aircraft fuselage having a circular or “blended circular arc” cross-section, and consequently, can also provide a cross-section-parasite-drag-per-seat ratio and an empty-weight-per-seat ratio that, in a first-order analysis, are comparable to those of the corresponding single-aisle fuselage cross-section, while offering better passenger comfort and owner revenue options.
However, achieving an optimized, lightweight structure for such near-elliptical cross-section fuselages when they are constructed of composite materials, i.e., reinforcing fibers embedded in resin matrices, presents substantial engineering design challenges, not only because of the application of such materials to this relatively new application, but also because of the structural and weight penalties involved in moving from a fuselage design having a conventional circular cross-section to a fuselage design having a non-circular cross-section, especially those associated with the internal pressurization effects inherent in the design of high-altitude jet airliners.
Accordingly, there is a need in the aviation industry for design methods and techniques for achieving lightweight structures for pressurized, composite-body aircraft fuselages having an elliptical or a near-elliptical cross-section.